When I moved to New Zealand, I was amazed by my coworkers' candor. Marital status, kids, hobbies, salary are all interview questions here. At first I was terrified. In New York I kept my life cantoned from work. When so much as an opinion can get you fired, I couldn't leave any personal information to chance. Like you, I never friended coworkers on facebook. I even went so far as to develop a whole online presence under a pen-name for my personal hobbies.
Here in New Zealand, people genuinely care about each other. Now most of my coworkers are also facebook friends. It is very difficult to get fired here for any reason.
It was good to move to a culture where whole-self is expected rather than avoided. That will never happen in America.